Hi, as i have just brought this monitor and as it was a misery to make it run like at 120Hz, here's an howto do it with all steps i've done to achieve it (so someone with another monitor model might follow them to achieve that with his monitor too)
I won't speak about 3D output, as i don't brought it for that, but just to get a monitor that refresh closer to what my poor old Vision Master Pro was doing and saved my eyes, so i don't own 3D glasses.
step1: Finding the monitor EDID infos
Actually this step is not really necessary, because just forcing the 120Hz is enough to make it work as nvidia drivers will query EDID to get that value, but i like to know what are these settings to know what i could try for other modeline in non-native resolution. You can just skip to step 2 without setting any modeline infos and this should work.

I've found a program in the tree (emerge -a read-edid) that should read EDID infos from the monitor and tell me what i need to configure xorg, great !
But for some reason, the program wasn't able to read the infos

Monitor and video card combination does not support DDC1 transfers
Monitor and video card combination does not support DDC2 transfers
0 seconds per 128 byte EDID block transfer
Screen is not blanked during DDC transfer

The EDID data should not be trusted as the VBE call failed
Error: output block unchanged

After (hours) of search in google, and testing, i've found a simple solve, nvidia-settings have an option to save the edid infos it get from the monitor.
Here's where to get it (i will gave it anyway, but it's for people with a different monitor that wish get it the same way i did)
- Goto GPU0 (well the gpu where the monitor is attach to)
- Select the monitor (should be DFP-0 or DFP-1, monitor name is show there)
- And hit the "Acquire EDID" button
Now select binary format to save the EDID infos (because if you choose the text format, you'll get an hex dump of the edid, not something useful for human, and this text format also cannot be use with parse-edid that comes with get-edid program).
Now that we have the good edid infos in binary format, parse-edid is able to tell us the infos we are seeking (show for ones that don't own an nvidia but still need the EDID infos) :

Step 2: Setting your xorg.conf
I'll show you only the part that are need, other settings are upto you, the only thing important is to use 1680x1050_120 (because if you notice i've change the modeline name to 1680x1050_120 in it)

LOL it still doesn't work.
This time google gave me the answer, it's because nvidia drivers always start with GPU scaling enable for each monitor, and this prevent the monitor to work by itself.
All google answers says you need to load the nvidia-settings config file while booting : ie make the config file without the GPU scaling enable, quit (it autosave it), and use nvidia-settings -l
But because on my computer the nvidia-settings bug when using the -l switch, it try to use the display from my host:display instead of using the DISPLAY env return value

So because of that and because i frankly don't care to check everytime i run the nvidia-settings GUI if it reenable the GPU scaling shit everytime, i will use the direct query instead (and it's possible hopefuly !).
This will do what we need, and specially without that bug.

Step 4: Disabling GPU Scaling
You will have to run that evertime X is run, so find where you wish add it, for me i simply add it as a start program in gnome.
And you will have to do that for each monitors (DFP-0 and DFP-1 if you have two)

And now xrandr and xvidtune output to show how X see that. xvidtune show twice Dot Clock speed, but it could just be because i use two monitors, and xrandr is lost, gnome screen size use the xrandr info, and will then only allow you to get frequencies report by xrandr.

It is another tool in portage, hwinfo, the Suse hardware recognition tool. It doesn't show the same informations: I get only one mode with nvidia-settings and several with hwinfo. The plus with nvidia-settings and parse-edid is than the info is formatted for inclusion in xorg.conf.

Also, a strange result of both ways is than I don't get the current screen mode:

My current mode is 1600x1200@75Hz. I get it with another Suse tool: during a Suse installation, one of the final steps is to optionally read the monitor installation CD. That way, Yast is able to retrieve all the mode informations supported by the monitor and will write them into xorg.conf. This is a huge list of modes including a 1280x1024@88Hz mode._________________[[[ To any NSA and FBI agents reading that text: please consider ]]]
[[[ whether defending the US Constitution against all enemies, ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

According to nvidia-settings, my monitor can do 1600x1024@75, 70, 68, 65 and 60Hz. It is no 50Hz mode for that resolution. Also, it is no 1280x1024#52Hz mode. Even 2048x1536 is at 60Hz. I will soon try with another one monitor, a LCD screen.

What would be great with nvidia-settings and parse-edid is that they would be able to output all the modes that show nvidia-settings._________________[[[ To any NSA and FBI agents reading that text: please consider ]]]
[[[ whether defending the US Constitution against all enemies, ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]